1. Field of the Invention
The present invention relates to a fuzzy neuron which can be used in the field of pattern recognition such as image recognition, voice recognition and the like.
2. Description of the Prior Art
A fuzzy neuron extracts the characteristic data of a pattern by means of characteristic division lines and performs a fuzzy operation on the pattern characteristic data and a membership function to thereby achieve pattern recognition.
Referring to the above-mentioned characteristic division lines, normally, a plurality of straight lines disposed in a horizontal or vertical direction are used in common in all recognition target patterns. In other words, the shape, position, number and the like of the characteristic division lines are not changed according to the target patterns. For example, in Unexamined Japanese Patent Publication (Kokai) Hei-2-310782 (which is hereinafter referred to as reference 1) and Yamakawa: "A Fusion of Fuzzy Logic and Neuroscience--A Fuzzy Neuron Chip and Its Application to a Pattern Recognition System--" International Fuzzy System Association (IFSA) '91 (which is hereinafter referred to as reference 2), in order to recognize handwritten figures which range from 0 to 9, there are arranged seven linear characteristic division lines CDL1 to 7 as shown in FIGS. 4A to 4D, which lines are used in common with respect to all of the figures. However, this is only for the purpose of simplification of the system and thus this is not a restraint based on the principles of the fuzzy neuron.
In fact, according to the reference 1, it is preferable to select the optimum characteristic division lines according to the target patterns and, as the preferable examples, there are illustrated parabolic characteristic lines (CDL 1 to 4 in FIG. 5A) with respect to a FIG. "0", or there are shown concentric characteristic lines (CDL 1 to 3 in FIG. 5B) with respect to an English letter "X".
However, in either of the references 1 and 2, there is not shown any means which can change the characteristic division lines according to the target patterns. Also, a realized example of such means has never been reported so far.
When the patterns to be treated are small in number and simple like the handwritten figures, it is not so difficult to set characteristic division lines which are common to all of the patterns. However, the more the patterns increase in number, or the more complicated the patterns are, the more difficult it is to set the common characteristic division lines.
If a large number of characteristic division lines are set in order to cover all patterns, then there are present many characteristic division lines which are of no use for individual patterns, resulting in a wasteful system. Even if there is provided a signal which prevents an operation from being executed on the unnecessary characteristic division lines, as in an embodiment shown in the reference 1, it cannot be denied that the loss of processing time is produced. On the other hand, if the number of the characteristic division lines is minimized, then the characteristics of the individual patterns cannot be taken up, which leads to a lowered rate of recognition.
The above-mentioned problems found in the prior art are caused by an unreasonable idea that the characteristic division lines are used in common to all patterns. It is desirable that the characteristic division lines can be set arbitrarily in the position, shape, number and the like thereof for every pattern so as to be able to extract best the characteristics of the patterns.